3
provide a bit more insurance in our own airborne radio installations,
we used heavy-duty aftermarket On/Off switch assemblies in our
prototypes.
And once again, these are available from Maxx
Products.
Maxx calls this switch their "Soft Mount One-Piece
Charge Switch" - P/N 3470. This well-built switch also allows the
airborne battery packs to be charged externally, directly from the
covered charge jack in the switch itself. This switch also includes
a silicon pad soft-mount - very desirable in large gas-powered
models. We used three (3) of these switch assemblies in our Edge
540T models - one for each of the two redundant receivers and
their battery packs, and a third switch for the engine ignition battery
pack.
(NOTE: The manufacturer's part numbers provided in this manual were correct and
current as of it's writing. Part numbers and/or products are subject to change.)
Engine Selection
At 33%, the SIG Edge 540T ARF model is obviously very large.
Typical flying weights can vary with different engines, airborne
equipment, and batteries but in general, fall within 26 to 27-1/2
pounds, ready to fly. We have flown and tested our prototypes
using the very powerful and compact F.P.E. 6.8 ci (111.4 cc) twin
cylinder gas engine. The F.P.E. 6.8 Twin weighs 116 ounces (3289
grams), including the electronic ignition module and mufflers that
come with the engine. This very smooth running engine, turning a
Biela 27 x 10 composite propeller, produces about 11.5 hp @ 6000
rpm. This translates to approximately 75 pounds of static thrust!
This is precisely the kind of power-to-weight ratio that makes the
SIG Edge 540T a very capable 3D aircraft.
The SIG Edge 540T design incorporates a large and spacious
fiberglass cowl. This cowl is large enough to fully enclose the
F.P.E. 6.8 twin cylinder engine, including the rubber sparkplug
boots. This means that with the exception of creating the required
clearance holes for the two stock mufflers and opening the bottom
rear half-round air dump, there are no other required cowl
openings.
If you choose to power your Edge 540T with a different brand of
gas engine, then we suggest using engines in the 95 to 110cc
range. Again, when choosing an engine for your Edge, other than
the F.P.E. 6.8 twin, you should carefully consider the weight of the
engine and the overall mounting dimensions. To assist you, the
following dimensions are provided:
1) Firewall to front spinner opening surface of cowl: 7-7/32" (this
can be adjusted fore or aft by about 1/8")
2) Maximum (non-contact) internal cowl width: 13-1/16"
We urge you to carefully consider the engine you choose for your
Edge 540T ARF model. Reliability, power, weight, and dimensions
are all very important in obtaining maximum performance and a
long life for your model. Finally, under no circumstances do we
recommend any engine for this model in excess of 111.4cc
displacement.
Covering
The SIG Edge 540T ARF model has been professionally covered
with SIG AeroKote
®
covering film.
This high quality polyester
covering film has been expertly applied, using a beautiful and
unique trim scheme, designed specifically to provide maximum
contrast between the top and bottom of the model. This feature
offers excellent attitude reference during 3D or IMAC maneuvers.
The SIG Edge 540T ARF model was manufactured and covered in
a part of the world that is typically humid. When the individual
covered parts are removed from their plastic bags, some wrinkling
of the covering may occur after a day or so. This is especially
possible if you live in a drier climate.
This phenomenon is
perfectly normal and DOES NOT mean that your model has a
defect. These wrinkles are caused by wood losing moisture and
dimensionally shrinking in the process. This is the nature of wood,
especially softer types.
Some modelers may feel that the covering on their ARF model
should be perfect and that they should not be expected to re-shrink
wrinkles. This is not realistic, because any covering material -
regardless of brand - that has been hand applied over wood, is
indeed subject to the possibility of wrinkling.
The requirement is to therefore re-shrink the covering, as needed.
This is not difficult to do and can be done using normal hobby-type
covering tools, such as a heat iron, a trim seal tool, and a heat gun.
Carefully note that we do not recommend the use a heat gun
around any areas where two pieces of covering material have
been seamed together. The heat gun generates a great deal of
broadcast type heat that in turn, can loosen seamed covering
material, causing these seams to "creep". If you must use a heat
gun around or near such seams, we urge you to protect them first.
To do this, simply soak some paper towels in cool tap water and
arrange them directly onto the seams. You can then use your heat
gun to carefully shrink areas close to the seam.
When using a hobby-type heat iron, we always suggest that the
surface of the shoe be covered with a soft cloth. This will help to
prevent scratching or hazing the surface of the covering material.
For years we have used old cotton T-shirt cloth for this purpose and
it works very well. There are also commercially available "covering
socks" that fit onto most covering iron shoes. These can vary in
quality, so choose one that feels the softest. Also note that the
temperatures required to shrink and seal AeroKote
®
(275
O
- 325
O
F) are definitely high enough to melt or distort plastic parts. Use
common sense when working around the plastic parts on your
model!
Also be aware that the aft top turtledeck on the Edge 540T ARF
model is a composite of shaped white foam, sheeted with
balsawood. This makes for a very light structure, eliminating the
need for stringers. However, we do suggest that you only use a
heat iron on this area for re-shrinking purposes, and then, only
lightly.
For reference, the SIG Edge 540T ARF model was covered using
the following AeroKote
®
colors and SIG part numbers:
Blue Opaque ................................................................#SIGSTL250
Bright Yellow Opaque ..................................................#SIGSTL330
Black Opaque (Striping) ..............................................#SIGSTL201
Yellow/Black Checkerboard (1" sq.) Fin/Rudder ..........#SIGSTL432